An assessment of patient health is often based, in part, on the chemistry of one or more bodily fluids of that patient, such as blood, urine, spittle, tears, etc. Blood, for example, provides many key health markers, for example, such as hemoglobin (red blood cell) count, white-blood-cell (WBC) count, nitrogen level, glucose level, and ion concentration, among others.
Unfortunately, the collection of bodily fluids in volumes sufficient for reliable testing can be challenging. For example, conventional blood-test samples are usually drawn in-vivo using large medical syringes, which can cause significant patient distress—before, during, and after the drawing procedure.
Blood drawing methods are highly manual in nature and typically require trained personnel who can properly select a vein suitable for needle insertion and extract the blood into one or more sample vials. It is not uncommon that, during a blood draw, the skin is punctured but the target vein is missed. In such cases, the needle must be removed and reinserted in a second attempt to hit the proper vein. In other cases, the needle is inserted into the target vein too deeply. As a result, the other end wall of the target vein is punctured, which can cause blood leakage under the skin to give rise to a hematoma.
To avoid some of the complications of in-vivo blood drawing, a blood sample can be acquired ex-vivo using a lancelet to puncture the skin at a location that can provide a sufficient amount of blood—typically, a fingertip. Unfortunately, this method also has many disadvantages. First, lancelet-based blood drawing typically yields only a small amount of blood before clotting occurs. The presence of a blood clot in a blood sample is a cause for rejection of the sample because testing of partially clotted blood can lead to irregularities in some blood tests. Second, sites that are prone to provide more blood when pierced also tend to have a high concentration of pain receptors. As a result, a puncture of the skin at these sites typically causes the patient more pain.
Both blood-drawing methods cause significant pain to the patient, weep internally and externally afterward, give rise to potential infection sites, and are prone to bruising and prolonged tenderness. As a result, patients are understandably unenthusiastic about having their blood drawn.
Further, a typical test panel requires several milliliters (or tens of milliliters) of blood. This is true for other bodily fluids—urine, spittle, synovial fluid, moist solids, etc., which, in many cases, can be difficult to collect from the patient in sufficient volume.
The need to enable sophisticated analysis of a bodily fluid using only a small volume of fluid and without subjecting a patient to significant pain or risk of complication remains, as yet, unmet.